This invention relates to bioerodible deodorant formulations for use on the human body employing the controlled release of water-soluble cationic germicides from hydrophobic carboxylic acid polymer matrices. A broad spectrum of germicide release rates is achieved by varying the choices of matrix and germicide and the loading levels.
The sustained delivery of drugs and other materials for the treatment of the human body has been a major area of research during recent years. The various types of sustained drug delivery developments can be broadly classified into diffusional, osmotic, and erosional. In the first two of these, the delivery rate of the drug or other treating material is essentially independent of the biological environment and hence can be predicted on theoretical principles. However, unless a diffusional or osmotic delivery system is capable of bioerosion, some means must be provided for its removal once its delivery role has been completed. Since there are applications in which this is not feasible or convenient, there has existed a need for systems that can controllably deliver a treating material by erosion, yielding only toxicologically acceptable degradation products.
One simple approach to a bioerodible delivery system is to disperse or dissolve the material to be delivered in a natural or synthetic water-soluble polymer. Upon dissolution of the polymer in an aqueous medium, the drug or other material is delivered at a rate which can be controlled to some extent by choice of the polymer and treating material. Another approach is to control the dissolution rate of a water-soluble polymer in such a system by the introduction of hydrolyzable chemical cross-links resulting in a hydrophilic gel that slowly erodes as the cross-links are broken. The use, however, of a water-soluble polymer as a major constituent yields a very hydrophilic polymer matrix that will be completely permeated by water leading to leaching of the treating material. In such a system, release of the drug or other treating material from the matrix will be principally determined by drug diffusion and water solubility.
A more desirable approach involves the use of hydrophobic, water-insoluble polymers capable of releasing a treating material by erosion of the matrix with only a minimal amount of release by diffusion. Where the erosion process can be confined to the polymer-water interface and where the total area of the polymer matrix does not significantly change with time, constant or zero order release kinetics can be expected. The delivery rates from such a system can be controlled by simply varying drug loading and/or the matrix erosion rate.
The use of hydrophobic polymers which are solubilized by ionization of a pendent carboxyl group with consequent dissolution and drug release are well known. Among the publications dealing with such systems is U.S. Pat. No. 3,811,444, which describes an ocular insert for the continuously controlled administration of a therapeutically effective dosage of drug to the eye over a prolonged period of time. Also relevant is U.S. Pat. No. 3,608,063 disclosing sustained release pharmaceutical compositions prepared by combining, in the presence of water and a carboxylic acid, a polymer having acidic or basic functionality with a pharmaceutically active material having, respectively, basic or acidic functionality to yield a product having sustained release, enteric, and delayed-release properties.
Although apparently not based upon any sustained release capability of the compositions described, U.S. Pat. No. 3,956,480 is relevant in that it describes a treatment of teeth by the sorption onto tooth surfaces of a combination of a cationic germicide and an anionic polymer. Relevant, because of its cosmetic application, is the teaching of South African Pat. No. 751473 which discloses antiperspirant compositions containing as an ingredient a perspiration-absorbing polymer such as a copolymer of polyvinylmethylether and maleic anhydride. The compositions may contain, as an additional ingredient, a variety of germicides. There is no teaching with respect to any sustained release properties inherent in the compositions.